Preparation process of solid wood core baking varnish door plate

Abstract

The present application belongs to the technical field of baking paint door plate, and discloses a preparation process of solid wood core baking paint door plate. The present application comprises the following steps: firstly, combining polygonal solid wood strips into a solid wood blank, then hot-pressing, double-side sanding, vacuumizing, soaking with a wood reinforcing agent, solidifying, sanding, and obtaining a pretreated solid wood plate; secondly, coating a sealing primer on the pretreated solid wood plate, then spraying white primer and polishing, spraying a layer of white primer and polishing, spraying three layers of finish paint, and finally spraying varnish, polishing, drying, polishing, and edge sealing, and obtaining the solid wood core baking paint door plate. The wood reinforcing agent prepared from hydrophilic nano-silica aerogel powder, modified water-based polyurethane dispersion, and microencapsulated ammonium polyphosphate, and the introduction of synergist in the varnish layer effectively improve the paint film hardness, anti-cracking ability, anti-deformation ability, and fireproofing ability. Therefore, the present application has a more extensive application prospect.

Description

Technical Field

[0001] This invention belongs to the field of painted door panel technology, specifically relating to a preparation process for a solid wood core painted door panel. Background Technology

[0002] Solid wood core lacquered door panels use multi-layer solid wood boards, particleboard, or spliced ​​boards as the base material. The surface undergoes multiple lacquering processes (such as three coats of base coat, three coats of top coat, and two coats of clear coat, followed by high-temperature baking) to create a mirror or matte finish. Due to their high color saturation and gloss, they are suitable for modern, minimalist, and luxurious styles. Furthermore, their dense lacquer film can resist kitchen grease and moisture, making them widely used in kitchen cabinets and other applications.

[0003] However, in practical applications, solid wood core painted door panels still suffer from insufficient paint film hardness, leading to easy scratches on the paint surface; as well as poor fire resistance and susceptibility to cracking and deformation during temperature and humidity changes. Therefore, the paint film hardness, crack resistance, deformation resistance, and fire resistance of existing solid wood core painted door panels still need to be improved. Summary of the Invention

[0004] To address the shortcomings mentioned in the background section, the present invention aims to provide a manufacturing process for solid wood core painted door panels, solving the following technical problems:

[0005] Existing solid wood core painted door panels still suffer from poor paint film hardness, crack resistance, deformation resistance, and fire resistance.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A manufacturing process for a solid wood core painted door panel includes the following steps:

[0008] S1: Polygonal solid wood strips are assembled into solid wood board blanks, then hot-pressed, sanded on both sides, vacuumed, then soaked in wood strengthening agent, removed, cured and sanded to obtain pre-treated solid wood boards;

[0009] S2: After applying a sealing primer to the pre-treated solid wood board, spray white primer and sand it. Then spray another layer of white primer and sand it. Then spray three layers of topcoat. Finally, spray clear varnish and sand, dry, polish and seal the edges to obtain a solid wood core painted door panel.

[0010] The wood reinforcing agent is prepared from deionized water, sodium polycarboxylate, defoamer, hydrophilic nano-silica aerogel powder, modified waterborne polyurethane dispersion, water-soluble epoxy resin, penetrant, and microencapsulated ammonium polyphosphate.

[0011] The modified waterborne polyurethane dispersion is prepared from polyether diol, diphenylmethane diisocyanate, acetone, dimethylolpropionic acid, trimethylolpropane, triethylamine, and deionized water.

[0012] The microencapsulated ammonium polyphosphate is a microcapsule with corn starch and gum arabic as the composite wall material and ammonium polyphosphate as the core material.

[0013] The varnish is made from polyurethane acrylate, photoinitiator, tripropylene glycol diacrylate, defoamer, leveling agent, and synergist.

[0014] The synergist is prepared from tripropylene glycol diacrylate, epoxy acrylate, nano alumina, nano boron nitride, silane coupling agent KH-560, dispersant, and defoamer.

[0015] Preferably, the preparation method of the wood reinforcing agent is as follows:

[0016] Sodium polycarboxylate and mineral oil defoamer are added to deionized water and stirred for 5-10 minutes. Then, while stirring, hydrophilic nano-silica aerogel powder is added and stirred at 1400-1500 rpm for 30-50 minutes. Next, it is sheared at 10000 rpm for 15-20 minutes and ultrasonically dispersed for 20-30 minutes. Then, modified waterborne polyurethane dispersion, water-soluble epoxy resin, and penetrant are added sequentially, stirring for 10-20 minutes after each addition. Finally, microencapsulated ammonium polyphosphate is added and stirred at 200-250 rpm for 40-60 minutes. After standing and maturing for 12-14 hours, it is passed through a 200-mesh sieve to obtain the wood reinforcing agent.

[0017] Preferably, the mass ratio of the deionized water, sodium polycarboxylate, mineral oil defoamer, hydrophilic nano silica aerogel powder, modified waterborne polyurethane dispersion, water-soluble epoxy resin, penetrant JFC-M, and microencapsulated ammonium polyphosphate is 60:0.8:0.3-0.5:3-3.5:30:5:1.5-2:7-9.

[0018] Preferably, the synergist is prepared by the following method:

[0019] Add silane coupling agent KH-560 to tripropylene glycol diacrylate and stir for 10-20 min. Then add nano alumina and nano boron nitride and stir for 1-2 h. After ultrasonic dispersion for 30-40 min, add defoamer and stir for 20-30 min. Then add epoxy acrylate and dispersant and stir for 40-60 min. Grind to a fineness of 5-10 μm and filter to obtain the synergist.

[0020] Preferably, the mass ratio of the tripropylene glycol diacrylate, silane coupling agent KH-560, nano alumina, nano boron nitride, defoamer, epoxy acrylate, and dispersant is 35:3-4:15:10:0.4-0.6:35:2-2.5.

[0021] Preferably, the preparation method of the microencapsulated ammonium polyphosphate is as follows:

[0022] Corn starch and gum arabic were added to deionized water and stirred at 80-85℃ for 30-50 min. After cooling to 30-40℃, Tween-80 was added and stirred for 10-20 min. Then, ammonium polyphosphate aqueous dispersion was added and stirred at 300 r / min for 10-20 min, followed by stirring at 600-800 r / min for 20-30 min. The pH was adjusted to 4.0-4.5 with 5% citric acid aqueous solution. The mixture was then stirred at 300-500 r / min at 45-50℃ for 2-3 h, followed by incubation at 58-60℃ for 1-1.2 h. After cooling to room temperature, the mixture was centrifuged and the precipitate was washed 5-7 times with deionized water. The precipitate was vacuum dried at 55-60℃ for 8-10 h, pulverized, and passed through a 200-mesh sieve to obtain microencapsulated ammonium polyphosphate.

[0023] Preferably, the mass ratio of the deionized water, corn starch, gum arabic, Tween-80, and ammonium polyphosphate aqueous dispersion is 60-80:10-15:5-8:0.5-1:20;

[0024] The mass fraction of the ammonium polyphosphate aqueous dispersion is 50%.

[0025] The preferred method for preparing the modified waterborne polyurethane dispersion is as follows:

[0026] Polyether diol was dehydrated under vacuum at 98-100℃ and -0.09MPa for 2-2.5h. After cooling to 55-60℃, diphenylmethane diisocyanate and acetone were added, and the mixture was reacted at 78-80℃ for 2-2.5h. After cooling to 45-50℃, dimethylolpropionic acid and trimethylolpropane were added, and the mixture was reacted at 68-70℃ for 1.5-2h. After cooling to 35-40℃, triethylamine was added and stirred for 30-40min. Then, deionized water was added while stirring and the mixture was stirred for 30-50min. Acetone was removed by vacuum distillation at 40-45℃. The mixture was then filtered through a 100-mesh filter cloth to obtain the modified waterborne polyurethane dispersion.

[0027] Preferably, the mass ratio of the polyether diol, diphenylmethane diisocyanate, acetone, dimethylolpropionic acid, trimethylolpropane, triethylamine, and deionized water is 50:25:10:5:3:3.2-3.4:145-150.

[0028] Preferably, the preparation method of the varnish is as follows:

[0029] Polyurethane acrylate, photoinitiator TPO, photoinitiator 184, tripropylene glycol diacrylate, defoamer, and leveling agent are mixed evenly, and then synergist is added and stirred evenly to obtain a clear varnish.

[0030] The mass ratio of the polyurethane acrylate, photoinitiator TPO, photoinitiator 184, tripropylene glycol diacrylate, defoamer, leveling agent, and synergist is 50:2:1:45:0.3-0.5:0.3-0.5:6-7.

[0031] The beneficial effects of this invention are:

[0032] This invention provides a manufacturing process for solid wood core painted door panels. The invention effectively improves the paint film hardness, crack resistance, deformation resistance, and fire resistance of solid wood core painted door panels through the following methods.

[0033] (1) The hydrophilic nano-silica aerogel in the wood reinforcing agent of this invention can penetrate the pores of wood and combine with the fibers, thereby increasing the hardness of the substrate itself; the modified waterborne polyurethane and epoxy resin can enhance the bonding strength between wood fibers and improve the hardness of the product. The polymer in the wood reinforcing agent can form a cross-linked network with the wood fibers, restricting the free expansion and contraction of the fibers; the rigid filling of nano-silica can reduce the deformation space of wood under stress, improve the structural stability of wood, and inhibit bending or warping under load. The wood reinforcing agent can reduce the moisture absorption channels of wood through nano-filling, reducing the fluctuation of moisture content; at the same time, the elastic component of the polymer can buffer the internal stress caused by temperature and humidity changes, reduce the rate of moisture absorption and water loss of wood, and prevent the solid wood core painted door panel from cracking when the temperature and humidity change drastically. The microencapsulated ammonium polyphosphate in the wood reinforcing agent can release phosphate esters at high temperature to form a flame-retardant char layer and inhibit wood combustion. The modified waterborne polyurethane dispersion and nano-silica in the reinforcing agent can significantly reduce the water absorption rate of wood and improve the water resistance of solid wood core painted door panel.

[0034] (2) When the nano-alumina in the synergist of this invention is uniformly dispersed in the varnish coating, it forms countless "micro-scale support points" that directly resist coating deformation caused by external forces, greatly improving the surface scratch resistance; epoxy acrylate and dipropylene glycol diacrylate will further crosslink with polyurethane acrylate, making the coating molecular structure more compact, reducing the free movement of resin molecular chains, thereby improving the compressive strength and overall hardness of the coating. The silane coupling agent KH-560 in the synergist can eliminate the voids at the inorganic and organic interfaces, reducing the "interfacial peeling stress" caused by thermal expansion and contraction; nano-boron nitride can make the temperature distribution of the coating more uniform when heated, avoiding local overheating, thereby reducing overall deformation; the filling of nanoparticles will inhibit the thermal movement of resin molecular chains, reduce the coefficient of thermal expansion of the coating, and improve the resistance to deformation. The nano-alumina and boron nitride in the synergist can be uniformly dispersed in the coating, avoiding stress concentration at a single point and transforming localized high stress into overall low stress. The silane coupling agent KH-560 enhances the interfacial bonding force, preventing moisture and humidity from penetrating to the interface and causing inorganic particles to separate from the resin. The high cross-linking density of the coating structure is more stable, reducing its sensitivity to temperature and humidity changes and enhancing its crack resistance. The nano-alumina in the synergist melts rapidly at high temperatures to form a dense covering layer, isolating oxygen and heat from the wood substrate and slowing down the combustion rate. The nano-boron nitride has extremely high temperature resistance, allowing the boron nitride particles to maintain structural stability even at high temperatures, preventing the coating from melting and dripping. The highly cross-linked structure of the synergist and varnish forms a more stable "char layer" at high temperatures, which further hinders the spread of combustion. The uniform filling of nanoparticles in the synergist can fill the tiny pores in the coating and reduce water penetration; the siloxane groups of silane coupling agent KH-560 will form a weak hydrophobic layer on the coating surface, reducing the adsorption and penetration of water on the coating surface; the high cross-linking density of the coating structure can prevent water from swelling reaction with the resin molecular chains, thereby avoiding blistering and peeling of the coating due to water absorption.

[0035] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] In the description of this invention, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inner", "around", etc., which indicate orientation or positional relationship, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this invention.

[0038] Unless otherwise specified, the following information pertains to some of the raw materials used in the following embodiments and comparative examples of this invention:

[0039] Polyether diol was purchased from Shandong Baiqian Chemical Co., Ltd.; polyurethane acrylate was purchased from Shandong Yinglang Chemical Co., Ltd.; epoxy acrylate was purchased from Wuhan Xinxinjiali Biotechnology Co., Ltd.; water-soluble epoxy resin was purchased from Shanghai Koraman Reagent Co., Ltd.; hydrophilic nano silica aerogel powder was purchased from Shanghai Koraman Reagent Co., Ltd.; and tripropylene glycol diacrylate was purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0040] Example 1: The preparation process of a solid wood core painted door panel is as follows:

[0041] S1: Add 10g corn starch and 5g gum arabic to 60mL of deionized water and stir at 80℃ for 30min. After cooling to 30℃, add 0.5g Tween-80 and stir for 10min. Then add 20g of 50% ammonium polyphosphate aqueous dispersion and stir at 300r / min for 10min, then at 600r / min for 20min. Adjust the pH to 4.0 with 5% citric acid aqueous solution. Then stir at 300r / min at 45℃ for 2h, then keep warm at 58℃ for 1h. After cooling to room temperature, centrifuge and wash the precipitate 5 times with deionized water. After vacuum drying at 55℃ for 8h, pulverize and pass through a 200-mesh sieve to obtain microencapsulated ammonium polyphosphate.

[0042] S2: 50g of polyether diol was dehydrated under vacuum at 98℃ and -0.09MPa for 2h. After cooling to 55℃, 25g of diphenylmethane diisocyanate and 10g of acetone were added and reacted at 78℃ for 2h. After cooling to 45℃, 5g of dimethylolpropionic acid and 3g of trimethylolpropane were added and reacted at 68℃ for 1.5h. After cooling to 35℃, 3.2g of triethylamine was added and stirred for 30min. Then, 145g of deionized water was slowly added while stirring at 800r / min and stirred for 30min. The acetone was removed by vacuum distillation at 40℃. The mixture was filtered through a 100-mesh filter cloth to obtain the modified waterborne polyurethane dispersion.

[0043] S3: Add 0.8g sodium polycarboxylate and 0.3g mineral oil defoamer to 60g deionized water and stir for 5min. Then, while stirring, add 3g hydrophilic nano silica aerogel powder and stir at 1400r / min for 30min. Then, shear at 10000r / min for 15min and ultrasonically disperse for 20min. Then, add 30g modified waterborne polyurethane dispersion, 5g water-soluble epoxy resin, and 1.5g penetrant JFC-M in sequence, stirring for 10min after each addition. Then, add 7g microencapsulated ammonium polyphosphate and stir at 200r / min for 40min. After standing and aging for 12h, pass through a 200-mesh sieve to obtain the wood reinforcing agent.

[0044] S4: Add 3g of silane coupling agent KH-560 to 35g of tripropylene glycol diacrylate and stir for 10min. Then add 15g of nano alumina and 10g of nano boron nitride and stir for 1h. After ultrasonic dispersion for 30min, add 0.4g of defoamer BYK-052 and stir for 20min. Then add 35g of epoxy acrylate and 2g of dispersant BYK-2150 and stir for 40min. Grind with a three-roll mill to a fineness of 5μm. Finally, filter with a 100-mesh filter cloth to obtain the synergist.

[0045] S5: Mix 50g epoxy acrylate, 5g talc, 2g photoinitiator TPO, 1g photoinitiator 184, 40g tripropylene glycol diacrylate, 0.3g defoamer BYK-024, and 0.3g leveling agent Tego 410 evenly to obtain a sealing primer;

[0046] S6: Mix 30g polyurethane acrylate, 20g epoxy acrylate, 20g titanium dioxide, 10g barium sulfate, 3g photoinitiator TPO, 1g photoinitiator 184, 40g tripropylene glycol diacrylate, 0.4g defoamer BYK-024, and 1g dispersant BYK-2150 evenly, then grind with a three-roll mill until the pigment fineness is 5μm and filter with a 120-mesh filter cloth to obtain white primer;

[0047] S7: Mix 30g epoxy acrylate, 20g polyurethane acrylate, 3g photoinitiator TPO, 1g photoinitiator 184, 40g tripropylene glycol diacrylate, 0.3g defoamer BYK-024, and 0.3g leveling agent Tego 410 evenly. Then add 0.1g carbon black and stir at 800r / min for 20min. Then grind with a three-roll mill until the pigment fineness is 10μm and filter with a 120-mesh filter cloth to obtain the topcoat.

[0048] S8: Mix 50g polyurethane acrylate, 2g photoinitiator TPO, 1g photoinitiator 184, 45g tripropylene glycol diacrylate, 0.3g defoamer BYK-024, and 0.3g leveling agent Tego 410 evenly, then add 6g synergist and stir at 800r / min for 20min to obtain clear varnish;

[0049] S9: Polygonal solid wood strips are assembled into solid wood board blanks, cold-pressed at 0.5MPa for 30 minutes, then hot-pressed at 1.0MPa and 120℃ for 20 minutes to form the board. The board is then sanded on both sides with 180-grit sandpaper. After that, it is placed in a vacuum chamber and vacuumed to -0.08MPa and held for 30 minutes. Then, it is first immersed in wood reinforcing agent at normal pressure for 30 minutes, then pressurized to 1.2MPa and held for 2 hours. After that, the temperature is slowly increased to 80℃ at 1℃ / min and cured for 12 hours. After cooling to room temperature, it is finely sanded with 320-grit sandpaper. The surface wood chips are blown away with compressed air to obtain the pre-treated solid wood board.

[0050] S10: Apply a 30μm thick sealing primer to the pretreated solid wood board and level it at 40℃ for 3 minutes, with an energy of 800mJ / cm. 2 Cured under ultraviolet light for 60 seconds, followed by spraying a 40μm thick layer of white primer and leveling at 40℃ for 5 minutes, then cured at an energy of 800mJ / cm². 2 Curing is carried out under ultraviolet light for 60 seconds, then sanded with 300-grit sandpaper, and then the same white primer is sprayed again, leveled, cured, and sanded with 500-grit sandpaper to obtain a solid wood board with primer.

[0051] S11: First, spray a 20μm thick topcoat onto the primer-coated solid wood board and allow it to level at 40℃ for 5 minutes, then apply an energy of 1000mJ / cm². 2 Cured under ultraviolet light for 80 seconds, then two coats of the same topcoat were applied, followed by a 15μm thick clear coat and leveling at 40℃ for 3 minutes, with an energy of 1200mJ / cm². 2 After curing under ultraviolet light for 80 seconds, the wood is left to stand for 1 hour. Finally, it undergoes 800-grit dry sanding, 1200-grit wet sanding, 2000-grit secondary wet sanding, drying at 60℃, polishing and waxing, and edge sealing with PER waterproof edge sealing paper to obtain a solid wood core painted door panel.

[0052] Example 2: The preparation process of a solid wood core painted door panel is as follows:

[0053] S1: Add 12.5g corn starch and 6.5g gum arabic to 70mL of deionized water and stir at 83℃ for 40min. After cooling to 35℃, add 0.8g Tween-80 and stir for 15min. Then add 20g of 50% ammonium polyphosphate aqueous dispersion and stir at 300r / min for 15min, then at 700r / min for 25min. Adjust the pH to 4.3 with 5% citric acid aqueous solution. Then stir at 400r / min at 48℃ for 2.5h, then keep warm at 59℃ for 1.1h. After cooling to room temperature, centrifuge and wash the precipitate 6 times with deionized water. After vacuum drying at 58℃ for 9h, pulverize and pass through a 200-mesh sieve to obtain microencapsulated ammonium polyphosphate.

[0054] S2: 50g of polyether diol was dehydrated under vacuum at 99℃ and -0.09MPa for 2.2h. After cooling to 58℃, 25g of diphenylmethane diisocyanate and 10g of acetone were added and reacted at 79℃ for 2.2h. After cooling to 48℃, 5g of dimethylolpropionic acid and 3g of trimethylolpropane were added and reacted at 69℃ for 1.8h. After cooling to 38℃, 3.3g of triethylamine was added and stirred for 35min. Then, 148g of deionized water was slowly added while stirring at 800r / min and stirred for 40min. The acetone was removed by vacuum distillation at 43℃. The mixture was filtered through a 100-mesh filter cloth to obtain the modified waterborne polyurethane dispersion.

[0055] S3: Add 0.8g sodium polycarboxylate and 0.4g mineral oil defoamer to 60g deionized water and stir for 8min. Then, while stirring, add 3.3g hydrophilic nano silica aerogel powder and stir at 1450r / min for 40min. Then, shear at 10000r / min for 18min and ultrasonically disperse for 25min. Then, add 30g modified waterborne polyurethane dispersion, 5g water-soluble epoxy resin, and 1.8g penetrant JFC-M in sequence, stirring for 15min after each addition. Then, add 8g microencapsulated ammonium polyphosphate and stir at 230r / min for 50min. After standing and maturing for 13h, pass through a 200-mesh sieve to obtain the wood reinforcing agent.

[0056] S4: Add 3.5g of silane coupling agent KH-560 to 35g of tripropylene glycol diacrylate and stir for 15min. Then add 15g of nano alumina and 10g of nano boron nitride and stir for 1.5h. After ultrasonic dispersion for 35min, add 0.5g of defoamer BYK-052 and stir for 25min. Then add 35g of epoxy acrylate and 2.3g of dispersant BYK-2150 and stir for 50min. Then grind with a three-roll mill to a fineness of 8μm. Finally filter with a 100-mesh filter cloth to obtain the synergist.

[0057] S5: Mix 50g epoxy acrylate, 5.5g talc, 2g photoinitiator TPO, 1g photoinitiator 184, 40g tripropylene glycol diacrylate, 0.4g defoamer BYK-024, and 0.4g leveling agent Tego 410 evenly to obtain a sealing primer;

[0058] S6: Mix 30g polyurethane acrylate, 20g epoxy acrylate, 21g titanium dioxide, 11g barium sulfate, 3g photoinitiator TPO, 1g photoinitiator 184, 40g tripropylene glycol diacrylate, 0.5g defoamer BYK-024, and 1.2g dispersant BYK-2150 evenly, then grind with a three-roll mill until the pigment fineness is 8μm and filter with a 120-mesh filter cloth to obtain white primer;

[0059] S7: Mix 30g epoxy acrylate, 20g polyurethane acrylate, 3g photoinitiator TPO, 1g photoinitiator 184, 40g tripropylene glycol diacrylate, 0.4g defoamer BYK-024, and 0.4g leveling agent Tego 410 evenly. Then add 0.5g phthalocyanine blue and stir at 800r / min for 20min. Then grind the pigment with a three-roll mill until the pigment fineness is 12μm and filter it with a 120-mesh filter cloth to obtain the topcoat.

[0060] S8: Mix 50g of polyurethane acrylate, 2g of photoinitiator TPO, 1g of photoinitiator 184, 45g of tripropylene glycol diacrylate, 0.4g of defoamer BYK-024, and 0.4g of leveling agent Tego 410 evenly, then add 6.5g of synergist and stir at 800r / min for 20min to obtain a clear varnish;

[0061] S9: Polygonal solid wood strips are assembled into solid wood board blanks, cold-pressed at 0.5MPa for 30 minutes, then hot-pressed at 1.0MPa and 120℃ for 20 minutes to form the board. The board is then sanded on both sides with 180-grit sandpaper. After that, it is placed in a vacuum chamber and vacuumed to -0.085MPa and held for 30 minutes. Then, it is first immersed in wood reinforcing agent at normal pressure for 30 minutes, then pressurized to 1.4MPa and held for 2.5 hours. After that, the temperature is slowly increased to 85℃ at 1℃ / min and cured for 12 hours. After cooling to room temperature, it is finely sanded with 320-grit sandpaper. The surface wood chips are blown away with compressed air to obtain the pre-treated solid wood board.

[0062] S10: Apply a 40μm thick sealing primer to the pretreated solid wood board and level it at 45°C for 4 minutes, with an energy of 900mJ / cm². 2 Cured under ultraviolet light for 60 seconds, followed by spraying a 50μm thick layer of white primer and leveling at 45℃ for 8 minutes, then cured at an energy of 900mJ / cm². 2Curing is carried out under ultraviolet light for 60 seconds, then sanded with 350-grit sandpaper, and then the same white primer is sprayed again, leveled, cured, and sanded with 600-grit sandpaper to obtain a solid wood board with primer.

[0063] S11: First, spray a 25μm thick topcoat onto the primer-coated solid wood board and allow it to level at 45℃ for 8 minutes, then apply an energy of 1000-1200mJ / cm. 2 Cured under ultraviolet light for 80 seconds, then two coats of the same topcoat were applied, followed by a 18μm thick clear coat and leveled at 45℃ for 3-5 minutes at an energy of 1200mJ / cm². 2 After curing under ultraviolet light for 80 seconds, the wood is left to stand for 1 hour. Finally, it undergoes 800-grit dry sanding, 1200-grit wet sanding, 2000-grit secondary wet sanding, drying at 60℃, polishing and waxing, and edge sealing with PER waterproof edge sealing paper to obtain a solid wood core painted door panel.

[0064] Example 3: The preparation process of a solid wood core painted door panel is as follows:

[0065] S1: Add 15g corn starch and 8g gum arabic to 80mL of deionized water and stir at 85℃ for 50min. After cooling to 40℃, add 1g Tween-80 and stir for 20min. Then add 20g of 50% ammonium polyphosphate aqueous dispersion and stir at 300r / min for 20min, then at 800r / min for 30min. Adjust the pH to 4.5 with 5% citric acid aqueous solution. Then stir at 500r / min for 3h at 50℃ and keep warm at 60℃ for 1.2h. After cooling to room temperature, centrifuge and wash the precipitate 7 times with deionized water. After vacuum drying at 60℃ for 10h, pulverize and pass through a 200-mesh sieve to obtain microencapsulated ammonium polyphosphate.

[0066] S2: 50g of polyether diol was dehydrated under vacuum at 100℃ and -0.09MPa for 2.5h. After cooling to 60℃, 25g of diphenylmethane diisocyanate and 10g of acetone were added and reacted at 80℃ for 2.5h. After cooling to 50℃, 5g of dimethylolpropionic acid and 3g of trimethylolpropane were added and reacted at 70℃ for 2h. After cooling to 40℃, 3.4g of triethylamine was added and stirred for 40min. Then, 150g of deionized water was slowly added while stirring at 800r / min and stirred for 50min. The acetone was removed by vacuum distillation at 45℃. The mixture was filtered through a 100-mesh filter cloth to obtain the modified waterborne polyurethane dispersion.

[0067] S3: Add 0.8g sodium polycarboxylate and 0.5g mineral oil defoamer to 60g deionized water and stir for 10min. Then, while stirring, add 3.5g hydrophilic nano silica aerogel powder and stir at 1500r / min for 50min. Then, shear at 10000r / min for 20min and ultrasonically disperse for 30min. Then, add 30g modified waterborne polyurethane dispersion, 5g water-soluble epoxy resin, and 2g penetrant JFC-M in sequence, stirring for 20min after each addition. Then, add 9g microencapsulated ammonium polyphosphate and stir at 250r / min for 60min. After standing and maturing for 14h, pass through a 200-mesh sieve to obtain the wood reinforcing agent.

[0068] S4: Add 4g of silane coupling agent KH-560 to 35g of tripropylene glycol diacrylate and stir for 20min. Then add 15g of nano alumina and 10g of nano boron nitride and stir for 2h. After ultrasonic dispersion for 40min, add 0.6g of defoamer BYK-052 and stir for 30min. Then add 35g of epoxy acrylate and 2.5g of dispersant BYK-2150 and stir for 60min. Then grind with a three-roll mill to a fineness of 10μm. Finally filter with a 100-mesh filter cloth to obtain the synergist.

[0069] S5: Mix 50g epoxy acrylate, 6g talc, 2g photoinitiator TPO, 1g photoinitiator 184, 40g tripropylene glycol diacrylate, 0.5g defoamer BYK-024, and 0.5g leveling agent Tego 410 evenly to obtain a sealing primer;

[0070] S6: Mix 30g polyurethane acrylate, 20g epoxy acrylate, 22g titanium dioxide, 12g barium sulfate, 3g photoinitiator TPO, 1g photoinitiator 184, 40g tripropylene glycol diacrylate, 0.6g defoamer BYK-024, and 1.5g dispersant BYK-2150 evenly, then grind with a three-roll mill until the pigment fineness is 10μm and filter with a 120-mesh filter cloth to obtain white primer;

[0071] S7: Mix 30g epoxy acrylate, 20g polyurethane acrylate, 3g photoinitiator TPO, 1g photoinitiator 184, 40g tripropylene glycol diacrylate, 0.5g defoamer BYK-024, and 0.5g leveling agent Tego 410 evenly. Then add 0.08g permanent yellow and stir at 800r / min for 20min. Then grind with a three-roll mill until the pigment fineness is 10μm and filter with a 120-mesh filter cloth to obtain the topcoat.

[0072] S8: Mix 50g polyurethane acrylate, 2g photoinitiator TPO, 1g photoinitiator 184, 45g tripropylene glycol diacrylate, 0.3g defoamer BYK-024, and 0.3g leveling agent Tego 410 evenly, then add 7g synergist and stir at 800r / min for 20min to obtain clear varnish;

[0073] S9: Polygonal solid wood strips are assembled into solid wood board blanks, cold-pressed at 0.5MPa for 30 minutes, then hot-pressed at 1.0MPa and 120℃ for 20 minutes to form the board. The board is then sanded on both sides with 180-grit sandpaper. After that, it is placed in a vacuum chamber and vacuumed to -0.095MPa and held for 30 minutes. Then, it is first immersed in wood reinforcing agent at normal pressure for 30 minutes, then pressurized to 1.5MPa and held for 3 hours. After that, the temperature is slowly increased to 90℃ at 2℃ / min and cured for 12 hours. After cooling to room temperature, it is finely sanded with 320-grit sandpaper. The surface wood chips are blown away with compressed air to obtain the pre-treated solid wood board.

[0074] S10: Apply a 50μm thick sealing primer to the pretreated solid wood board and level it at 50°C for 5 minutes, with an energy of 1000mJ / cm². 2 Cured under ultraviolet light for 60 seconds, followed by spraying a 60μm thick layer of white primer and leveling at 50℃ for 10 minutes, then cured at an energy of 1000mJ / cm². 2 Curing is carried out under ultraviolet light for 60 seconds, then sanded with 350-grit sandpaper, and then the same white primer is sprayed again, leveled, cured, and sanded with 600-grit sandpaper to obtain a solid wood board with primer.

[0075] S11: First, spray a 30μm thick topcoat onto the primer-coated solid wood board and allow it to level at 50°C for 10 minutes, then apply an energy of 1200mJ / cm². 2 Cured under ultraviolet light for 80 seconds, then two coats of the same topcoat were applied, followed by a 20μm thick clear coat and leveling at 50℃ for 5 minutes, with an energy of 1200mJ / cm². 2 After curing under ultraviolet light for 80 seconds, the wood is left to stand for 1 hour. Finally, it undergoes 800-grit dry sanding, 1200-grit wet sanding, 2000-grit secondary wet sanding, drying at 60℃, polishing and waxing, and edge sealing with PER waterproof edge sealing paper to obtain a solid wood core painted door panel.

[0076] Comparative Example 1:

[0077] Compared with Example 1, this comparative example only did not add "microencapsulated ammonium polyphosphate" in the preparation process of S3. All other steps and parameters were the same, and will not be repeated here. The final product was a solid wood core painted door panel.

[0078] Comparative Example 2:

[0079] Compared with Example 1, this comparative example only did not add "hydrophilic nano silica aerogel powder" in the preparation process of S3. All other steps and parameters were the same, and will not be repeated here. The final product was a solid wood core painted door panel.

[0080] Comparative Example 3:

[0081] Compared with Example 1, this comparative example only did not use "wood strengthening agent" to treat the solid wood board blank in the preparation process of S9. All other steps and parameters were the same, and will not be repeated in this comparative example. The final result was a solid wood core painted door panel.

[0082] Comparative Example 4:

[0083] Compared with Example 1, this comparative example only did not add a "synergist" in the preparation process of step 8. All other steps and parameters were the same, and will not be repeated here. The final product was a solid wood core painted door panel.

[0084] Performance testing:

[0085] Hardness measurement:

[0086] Referring to GB / T 6739-2021 standard, the hardness grades of the solid wood core painted door panels prepared in Examples 1-3 and Comparative Examples 1-4 of this invention were determined, and the results are shown in Table 1.

[0087] Determination of resistance to deformation:

[0088] Referring to GB / T 3324-2022 standard, the warpage (%) of the solid wood core painted door panels prepared in Examples 1-3 and Comparative Examples 1-4 of this invention was measured, and the results are shown in Table 1.

[0089] Determination of crack resistance:

[0090] Referring to GB / T 17657-2013 standard, the solid wood core painted door panels prepared in Examples 1-3 and Comparative Examples 1-4 of this invention were tested for whether cracks (including hairline cracks) appeared after being kept in a high temperature and high humidity stage (40℃, 90% relative humidity) for 12 hours and a low temperature and low humidity stage (-20℃, 30% relative humidity) for 12 hours, and after 5 cycles. The test results are shown in Table 1.

[0091] Fire resistance testing:

[0092] According to GB 8624-2012 standard, the fire performance rating of the solid wood core painted door panels prepared in Examples 1-3 and Comparative Examples 1-4 of this invention was determined, and the test results are shown in Table 1.

[0093] Water resistance test:

[0094] Referring to GB / T 1733-2020 standard, the solid wood core painted door panels prepared in Examples 1-3 and Comparative Examples 1-4 of this invention were tested to determine whether the paint film turned white, blistered, or peeled after being soaked in distilled water at 23°C for 48 hours. The test results are shown in Table 1.

[0095] Table 1: Performance test results of Examples 1-3 and Comparative Examples 1-4

[0096]

[0097] Data Analysis:

[0098] As can be seen from Table 1, the solid wood core painted door panel prepared according to the embodiments of the present invention has excellent hardness, deformation resistance, crack resistance, fire resistance and water resistance.

[0099] In Comparative Example 1, no microencapsulated ammonium polyphosphate was added during the preparation of the wood reinforcing agent; in Comparative Example 2, no hydrophilic nano-silica aerogel powder was added during the preparation of the wood reinforcing agent; and in Comparative Example 3, no wood reinforcing agent was used to treat the solid wood board blank. The results showed that Comparative Example 1 exhibited significantly lower fire resistance compared to the examples; Comparative Example 2 showed significantly lower hardness, deformation resistance, crack resistance, and water resistance; and Comparative Example 3 showed significantly lower hardness, deformation resistance, crack resistance, fire resistance, and water resistance. This indicates that the addition of microencapsulated ammonium polyphosphate can effectively improve fire resistance, the addition of hydrophilic nano-silica aerogel powder can improve hardness, deformation resistance, crack resistance, and water resistance, and the wood reinforcing agent treatment can simultaneously improve hardness, deformation resistance, crack resistance, fire resistance, and water resistance. Comparative Example 4 did not add any synergist during the preparation of the varnish. The results showed that its hardness, deformation resistance, crack resistance, fire resistance, and water resistance were significantly reduced compared to the example. This indicates that the addition of the synergist of the present invention can further improve the hardness, deformation resistance, crack resistance, fire resistance, and water resistance of the solid wood core painted door panel.

[0100] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0101] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A manufacturing process for a solid wood core painted door panel, characterized in that, Includes the following steps: S1: Polygonal solid wood strips are assembled into solid wood board blanks, then hot-pressed, sanded on both sides, vacuumed, then soaked in wood strengthening agent, removed, cured and sanded to obtain pre-treated solid wood boards; S2: After applying a sealing primer to the pre-treated solid wood board, spray white primer and sand it. Then spray another layer of white primer and sand it. Then spray three layers of topcoat. Finally, spray clear varnish and sand, dry, polish and seal the edges to obtain a solid wood core painted door panel. The wood reinforcing agent is prepared from deionized water, sodium polycarboxylate, defoamer, hydrophilic nano-silica aerogel powder, modified waterborne polyurethane dispersion, water-soluble epoxy resin, penetrant, and microencapsulated ammonium polyphosphate. The modified waterborne polyurethane dispersion is prepared from polyether diol, diphenylmethane diisocyanate, acetone, dimethylolpropionic acid, trimethylolpropane, triethylamine, and deionized water. The microencapsulated ammonium polyphosphate is a microcapsule with corn starch and gum arabic as the composite wall material and ammonium polyphosphate as the core material. The varnish is made from polyurethane acrylate, photoinitiator, tripropylene glycol diacrylate, defoamer, leveling agent, and synergist. The synergist is prepared from tripropylene glycol diacrylate, epoxy acrylate, nano alumina, nano boron nitride, silane coupling agent KH-560, dispersant, and defoamer.

2. The manufacturing process of the solid wood core painted door panel according to claim 1, characterized in that, The preparation method of the wood strengthening agent is as follows: Sodium polycarboxylate and mineral oil defoamer are added to deionized water and stirred until homogeneous. Then, while stirring, hydrophilic nano-silica aerogel powder is added and stirred for 20-30 minutes. Modified waterborne polyurethane dispersion, water-soluble epoxy resin, and penetrant are added sequentially and stirred. Microencapsulated ammonium polyphosphate is then added and stirred for 40-60 minutes. After standing for 12-14 hours, the mixture is sieved to obtain the wood reinforcing agent.

3. The manufacturing process of the solid wood core painted door panel according to claim 2, characterized in that, The mass ratio of the deionized water, sodium polycarboxylate, mineral oil defoamer, hydrophilic nano silica aerogel powder, modified waterborne polyurethane dispersion, water-soluble epoxy resin, penetrant, and microencapsulated ammonium polyphosphate is 60:0.8:0.3-0.5:3-3.5:30:5:1.5-2:7-9.

4. The manufacturing process of the solid wood core painted door panel according to claim 1, characterized in that, The preparation method of the synergist is as follows: Add silane coupling agent KH-560 to tripropylene glycol diacrylate and stir well. Then add nano alumina and nano boron nitride and stir to disperse evenly. Then add defoamer and stir well. Finally add epoxy acrylate and dispersant and stir for 40-60 minutes. Then grind and filter to obtain synergist.

5. The manufacturing process of the solid wood core painted door panel according to claim 4, characterized in that, The mass ratio of the dipropylene glycol diacrylate, silane coupling agent KH-560, nano alumina, nano boron nitride, defoamer, epoxy acrylate, and dispersant is 35:3-4:15:10:0.4-0.6:35:2-2.

5.

6. The manufacturing process of the solid wood core painted door panel according to claim 1, characterized in that, The preparation method of the microencapsulated ammonium polyphosphate is as follows: Corn starch and gum arabic were added to deionized water and stirred at 80-85℃ for 30-50 minutes. After cooling, Tween-80 was added and stirred well. Then, ammonium polyphosphate aqueous dispersion was added and stirred well. The pH was adjusted to 4.0-4.5 and stirred at 45-50℃ for 2-3 hours. Then, it was kept at 58-60℃ for 1-1.2 hours. After cooling, the mixture was centrifuged, the precipitate was washed, vacuum dried, pulverized, and sieved to obtain microencapsulated ammonium polyphosphate.

7. The manufacturing process of the solid wood core painted door panel according to claim 6, characterized in that, The mass ratio of the deionized water, corn starch, gum arabic, Tween-80, and ammonium polyphosphate aqueous dispersion is 60-80:10-15:5-8:0.5-1:20; The mass fraction of the ammonium polyphosphate aqueous dispersion is 50%.

8. The manufacturing process of the solid wood core painted door panel according to claim 1, characterized in that, The preparation method of the modified waterborne polyurethane dispersion is as follows: After vacuum dehydration of polyether diol, diphenylmethane diisocyanate and acetone are added and reacted at 78-80℃ for 2-2.5h. After cooling, dimethylolpropionic acid and trimethylolpropane are added and reacted at 68-70℃ for 1.5-2h. After cooling, triethylamine is added and stirred for 30-40min. Then, deionized water is added while stirring and stirred until homogeneous. After removing acetone by vacuum distillation, the mixture is filtered to obtain the modified waterborne polyurethane dispersion.

9. The manufacturing process of the solid wood core painted door panel according to claim 8, characterized in that, The mass ratio of the polyether diol, diphenylmethane diisocyanate, acetone, dimethylolpropionic acid, trimethylolpropane, triethylamine, and deionized water is 50:25:10:5:3:3.2-3.4:145-150.

10. The manufacturing process of the solid wood core painted door panel according to claim 1, characterized in that, The preparation method of the varnish is as follows: Polyurethane acrylate, photoinitiator TPO, photoinitiator 184, tripropylene glycol diacrylate, defoamer, and leveling agent are mixed evenly, and then synergist is added and stirred evenly to obtain a clear varnish. The mass ratio of the polyurethane acrylate, photoinitiator TPO, photoinitiator 184, tripropylene glycol diacrylate, defoamer, leveling agent, and synergist is 50:2:1:45:0.3-0.5:0.3-0.5:6-7.

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